1997 aquatic vegetation in Pools 4, 8, 13, and 26 and La Grange Pool of the UMRS 

Yin, Y., H. Langrehr, J. Nelson, T. Blackburn, T. Cook, and J. Winkelman. 2000. 1997
annual status report: Status and trend of submersed and floating-leaved aquatic
vegetation in thirty-two backwaters in Pools 4, 8, 13, and 26 and La Grange Pool of the
Upper Mississippi River System.  U.S. Geological Survey, Upper Midwest
Environmental Sciences Center, La Crosse, Wisconsin, June 2000.  LTRMP 2000-P002. 
19 pp. + Appendixes A B. (NTIS # PB2000-107875)

ABSTRACT

Thirty-two backwaters of the Upper Mississippi and Illinois Rivers were monitored for
the seventh consecutive year in 1997 to determine the status and trend of changes of
submersed and floating-leaved aquatic vegetation. Aquatic vegetation was sampled at
regularly spaced sites along permanent transects established in previous years. Species
compositions, frequencies of individual species, and the frequencies of sites that
supported aquatic vegetation in 1997 were calculated and compared with results from
previous years. The status and trend of aquatic vegetation in 1997 varied among the
thirty-two backwaters. In general, the frequencies of sites that supported aquatic
vegetation in 1997 in the backwaters of Pools 8 and 13 were at or near their highest
levels recorded since 1991. In contrast, the frequencies of sites that supported aquatic
vegetation in 1997 in the backwaters of Pools 4 were at or near their lowest levels
recorded since 1991, despite four of the eight backwaters being in better condition than
in 1996. Aquatic vegetation was rare in Pool 26 and La Grange Pool in the 1990s. The
monitored backwaters of Pool 26 and La Grange Pool represent the few places where
sizable aquatic vegetation beds were found in their respective river stretches when the
transects were established in 1991 and 1992. In 1997, aquatic vegetation was present in
two of the four backwaters of Pool 26. The other two backwaters of Pool 26 have not
supported aquatic vegetation since after a long-duration flood in 1993. Aquatic
vegetation was present in two of the four backwaters of La Grange Pool, but
disappeared completely from the third backwater in 1997 and from the fourth (a channel
border area) in 1995.

KEYWORDS

Annual report, aquatic, floating-leaved, LTRMP, Mississippi River, submersed,
vegetation